Characterisation of polyurethane coatings using thermoanalytical techniques

A two-pack polyurethane coating was analyzed using thermoanalytical techniq ues. The curing reaction, monitored using pressure differential calorimetry (PDSC), rheometry and dynamic mechanical analysis (DMA) shows the temperat ure dependency of activation energy and hence rate of curing. In-situ ATR-F TIR shows the formation of urethane linkage over time. The decomposition be havior carried out under non-isothermal mode using thermogravimetric analys is (TGA) shows bimodal behavior. The activation energies of the initial ste p (10% decomposition) from both iso and non-isothermal experiments are in v ery good agreement with each other. The use of dynamic mechanical analysis (DMA) shows the difference in glass transition behavior (T-g) and elastic m odulus (E') due to the different state of cure. Also the coating exhibits a very broad loss modulus peak (E ") indicating higher energy dissipation wi th deformation.